Me-doped Ti-Me intermetallic thin films used for dry biopotential electrodes: a comparative case study. - In: Sensors, ISSN 1424-8220, Bd. 21 (2021), 23, 8143, S. 1-17
In a new era for digital health, dry electrodes for biopotential measurement enable the monitoring of essential vital functions outside of specialized healthcare centers. In this paper, a new type of nanostructured titanium-based thin film is proposed, revealing improved biopotential sensing performance and overcoming several of the limitations of conventional gel-based electrodes such as reusability, durability, biocompatibility, and comfort. The thin films were deposited on stainless steel (SS) discs and polyurethane (PU) substrates to be used as dry electrodes, for non-invasive monitoring of body surface biopotentials. Four different Ti-Me (Me = Al, Cu, Ag, or Au) metallic binary systems were prepared by magnetron sputtering. The morphology of the resulting Ti-Me systems was found to be dependent on the chemical composition of the films, specifically on the type and amount of Me. The existence of crystalline intermetallic phases or glassy amorphous structures also revealed a strong influence on the morphological features developed by the different systems. The electrodes were tested in an in-vivo study on 20 volunteers during sports activity, allowing study of the application-specific characteristics of the dry electrodes, based on Ti-Me intermetallic thin films, and evaluation of the impact of the electrode-skin impedance on biopotential sensing. The electrode-skin impedance results support the reusability and the high degree of reliability of the Ti-Me dry electrodes. The Ti-Al films revealed the least performance as biopotential electrodes, while the Ti-Au system provided excellent results very close to the Ag/AgCl reference electrodes.
https://doi.org/10.3390/s21238143
Big Data Analytics APIs architecture for formative assessors. - In: 2021 IEEE Frontiers in Education Conference (FIE), (2021), insges. 9 S.
This Research to Practice Full Paper is driven by the question: Within limited time resources available to trainers in projects for Big Data Analytics (BDA) problems, how can they define project requirements for Formative Assessment (FA) actions? The paper suggests BDA APIs architecture as helping tool for formative assessors. It helps them effectively produce and adapt visual diagnostic reports for FA-actions in agile based requirements (i.e. features) definition. The paper presents two core architectures: Architecture for a parametrized feature-descriptor-system to define/refine a BDA API feature and its visual diagnostic reports, and an initial resources architecture for BDA API to initialize an analytics algorithm with its input big data sets. Clarifying visually the trainee's challenges (i.e. incremental features in a BDA API) is our main FA action. The FA action is designed based on Csikszentmihalyi's flow model to support a trainee in matching balance between his/her challenges and his/her skills. To test the architecture's functions, the paper has test setups for two formal projects (each has 1 to 6 trainees) and two informal projects (each has 1 to 3 trainees). The projects are to attack BDA problems in learning analytics and in image automatic classification. The test results show that the visual diagnostic reports produced by the trainers are very effective in clarifying visually incremental BDA API features not only for simple classifiers (i.e. classical data mining algorithms) but also for complex classifiers (i.e. deep learning algorithms). The results show also how visual diagnostic reports are easily produced for comparing the algorithm performances using different input big data sets, whereas other reports are produced for comparing performances between different algorithms, using one input data set. Related works are also discussed to show the architecture's differences and advantages. Its main advantages are: 1) it enables the trainers to use deep learning algorithms beside classical data mining algorithms in its BDA API parameterizable feature descriptors for visual diagnostic reports. 2) The descriptors can be extended, reused, shared, and scaled out to help trainers in other universities providing flow model based FA actions. 3) Finally, it has extensions to integrate other theoretical frameworks like Buckingham Shum and Deakin Crick's framework for dispositional learning analytics instead of the used flow model.
https://doi.org/10.1109/FIE49875.2021.9637431
Fractional-order parameter update law for adaptive control of integer-order systems. - In: The 2021 9th International Conference on Systems and Control (ICSC'21), (2021), S. 325-331
This contribution investigates the extension of the certainty equivalence based model reference adaptive control (MRAC) towards fractional-order parameter update laws. We use the infinite state representation of the fractional-order integral for constructing an integer-order Lyapunov function to derive the parameter update law. This renders the model reference error asymptotically stable.In comparison to the integer-order MRAC the fractional-order approach increases the robustness with respect to unstructured uncertainties and allows for higher adaptation rates due to the algebraic type of convergence. All the results are illustrated with a simulation example stabilizing the benchmark of the wing-rock dynamics.
https://doi.org/10.1109/ICSC50472.2021.9666578
Passivity-based control for the cart-pole in implicit port-Hamiltonian representation: an experimental validation. - In: 2021 European Control Conference (ECC), (2021), S. 2080-2085
This paper presents the design, analysis and experimental validation of a passivity-based control strategy for the local stabilization and swing-up of the well-known cart-pole system in implicit port-Hamiltonian representation. The stabilizing controller features the Interconnection and Damping Assignment Passivity-Based Control (IDA-PBC) method with an optimal local assignment. The swing-up controller is derived from the so-called energy-based control approach and underlines the stabilization of a level-set (homoclinic orbit). The combination of these controllers guarantees the swing-up and asymptotic stabilization of the upright pendulum position, as well as the desired cart location. The effectiveness of the proposed control scheme is verified via real-time experiments, and the results are compared with those from other authors.
https://doi.org/10.23919/ECC54610.2021.9655210
Observability analysis for spacecraft attitude determination using a single temperature sensor. - In: 2021 European Control Conference (ECC), (2021), S. 1438-1445
We consider the problem of spacecraft attitude determination using temperature data. Common algorithms fuse multiple temperature measurements to reconstruct the attitude. However, a single sensor already contains a lot of information due to the temperature dynamics inherent to the nonlinear structure. In this work a rigorous observability analysis is carried out to determine the configurations in which the combination of a single temperature sensor with angular velocity measurements is sufficient for estimating the entire attitude. We evaluate the observability properties of the different configurations and give recommendations for the best configurations.
https://doi.org/10.23919/ECC54610.2021.9654904
On the control design for the stabilisation of switched linear systems via eigenstructure assignment. - In: 2021 European Control Conference (ECC), (2021), S. 293-299
We are considering the control design problem for switched linear systems. We propose a method for the design of state-feedback controllers for the individual subsystems such that the closed-loop systems share a common eigenstructure. If additionally the eigenvalues of each individual subsystem can be chosen stable then the resulting switched system is stable for arbitrary switching. We present a necessary and a sufficient condition for which such controllers exist for systems of arbitrary order. For third-order systems, we show that a common eigenstructure can always be obtained by state-feedback given that the number of inputs offer enough degrees of freedom. We present a constructive procedure to obtain feedback controls such that the closed-loop systems have common eigenstructures. In all but one degenerated case the eigenvalues can be chosen arbitrarily such that the resulting closed-loop switched system is rendered asymptotically stable for arbitrary switching. We present an example for the degenerated case, where the eigenstructure may only be rectified if one of the closed-loop systems has a positive eigenvalue.
https://doi.org/10.23919/ECC54610.2021.9655006
Saying "Hi" to grandma in nine different ways : established and innovative communication media in the grandparent-grandchild relationship. - In: Technology, Mind, and Behavior, ISSN 2689-0208, (2021), insges. 1 S.
https://doi.org/10.1037/tms0000107
Peeling close to the orientability threshold - spatial coupling in hashing-based data structures. - In: Proceedings of the Thirty-Second Annual ACM-SIAM Symposium on Discrete Algorithms, (2021), S. 2194-2211
https://dl.acm.org/doi/10.5555/3458064.3458195
Planungsmethoden für eine sozial akzeptable Navigation von Assistenzrobotern. - Ilmenau : Universitätsbibliothek, 2021. - 1 Online-Ressource (xiii, 195 Seiten)
Technische Universität Ilmenau, Dissertation 2021
In den vergangenen Jahren wurde im Bereich der mobilen Assistenzrobotik auch das Themenfeld der sozial-akzeptablen Navigation weiterentwickelt. Dabei kommt zu den vorhandenen Herausforderungen der Navigation nun auch der Faktor Mensch hinzu. Aus dem Themenbereich der sozial-akzeptablen Navigation widmet sich die vorliegende Arbeit zwei Aspekten, wobei der Fokus immer auf einem mobilen Roboter liegt, welcher sich im häuslichen Umfeld bewegt. Der erste Aspekt der Arbeit behandelt, wie ein Roboter sich in einer häuslichen Umgebung bewegen soll. Dabei ist von Interesse, welche Pfade der mobile Roboter im Beisein eines Bewohners plant. Die wissenschaftliche Leistung der Arbeit ist, vorhandene Planungsansätze auf Raum und Zeit zu erweitern und es so zu ermöglichen, die Bewegung einer Person in die Planungsphase zu integrieren. Dazu werden simple Bewegungsprädiktionsmethoden untersucht und es wird eine mathematische Beschreibung entwickelt, die Bewegungsvorhersagen von Personen in die Planung mit einbezieht. Durch die so weiterentwickelten Planungsverfahren werden zwei Szenarien experimentell näher untersucht: A) frontales Heranfahren an eine Person, B) frühzeitiges Ausweichen einer entgegenkommenden Person. Im zweiten Aspekt der vorliegenden Arbeit wird auf ein bisher nur sehr wenig beachtetes Problem der mobilen Robotik eingegangen: wie findet ein mobiler Roboter für seine jeweilige - häufig nur abstrakt formulierbare - Aufgabe sinnvolle Zielpunkte in seiner Einsatzumgebung, ohne dass diese statisch vorgegeben sein müssen? Als Lösungsansatz wird in dieser Arbeit ein Verfahren vorgeschlagen, welches eine abstrakte Aufgabe auf mehrere Kriterien abbildet und diese nach Extrempunkten untersucht. Diese Extrempunkte ergeben einzeln oder in Kombination mögliche Zielpunkte des Roboters. Die wissenschaftlichen Beiträge sind, für dieses Verfahren zu untersuchen, welche mathematische Formulierung der Einzelkriterien sinnvoll ist, welche Ergebnisse eine Optimierung mit unabhängigen Einzelkriterien liefert (Pareto-Optimalität) bzw. welche Ergebnisse die Kombination der einzelnen Kriterien zu einer Gesamtfunktion erzielt werden können (Superpositionsprinzip). Durch den hier präsentierten Ansatz werden folgende zwei Szenarien für die häusliche Navigation experimentell untersucht: C) Beobachten einer Person, D) Finden einer Parkposition bei potentiellen Engstellen. Für alle Szenarien gilt: es soll insbesondere das Weltwissen des Roboters zur Lösungsfindung genutzt werden. Dies alles setzt eine Akquise von Umweltwissen durch den Roboter voraus. Hierzu werden in der Arbeit praktisch einsetzbare Verfahren vorgestellt, welche das nötige Umweltwissen zur Schätzung der Oberkörperpose, Beobachtbarkeit und Bewegungsprädiktion ermitteln können.
https://doi.org/10.22032/dbt.50287
Editorial: Dry electroencephalography for brain monitoring in sports and movement science. - In: Frontiers in neuroscience, ISSN 1662-453X, Bd. 15 (2021), 809227, S. 1-2
https://doi.org/10.3389/fnins.2021.809227